This application relates generally to high strength materials and more specifically to fiber reinforced composites.
Fiber reinforced composites, or more simply composites, are used in many applications where a high strength to weight ratio is desired. Composite materials are used in aerospace applications because of this desirable property. They are also used in a wide variety of other structures such as sporting goods.
Several methods of making composites are known. To make metal matrix composites, fiber is sometimes placed between metal foil. The fiber is woven or held together in sheets by a binder. When the structure, called a "preform", is exposed to heat under pressure, the metal and fiber are consolidated into a composite. The exact temperature and pressure used depends heavily on the specific alloy used to make the composite. The temperature is high enough to soften the metal but below its melting point. For example, for titanium, temperatures between 1400.degree. F. and 2000.degree. F. are used. Pressures sufficient to cause the softened metal to flow around the fiber are applied. Pressures in the range of 10,000 psi to 15,000 psi are conventionally used.
To make shapes such as rings, more complicated techniques are used. U.S. Pat. No. 4,900,599 issued Feb. 13, 1990 to Doble describes a method of making composites in the shape of a disk. U.S. Pat. No. 4,697,324 to Grant et al. describes an alternative method and shows rings made with non-uniform cross sections. U.S. Ser. No. 07/625,479 filed Dec. 11, 1990 in the name of Keck et al. (which is hereby incorporated by reference) describes an improved method of making a metal matrix composites, particularly in the shape of a ring.
It would, however, be desirable to improve the method of manufacturing composites in a variety of ways. It might be desirable to reduce the cost of manufacturing a composite. It might also be desirable to more simply produce a composite with a non-uniform cross section.